More header clean-up.
* en/header-split-cache-h-part-2: (22 commits)
reftable: ensure git-compat-util.h is the first (indirect) include
diff.h: reduce unnecessary includes
object-store.h: reduce unnecessary includes
commit.h: reduce unnecessary includes
fsmonitor: reduce includes of cache.h
cache.h: remove unnecessary headers
treewide: remove cache.h inclusion due to previous changes
cache,tree: move basic name compare functions from read-cache to tree
cache,tree: move cmp_cache_name_compare from tree.[ch] to read-cache.c
hash-ll.h: split out of hash.h to remove dependency on repository.h
tree-diff.c: move S_DIFFTREE_IFXMIN_NEQ define from cache.h
dir.h: move DTYPE defines from cache.h
versioncmp.h: move declarations for versioncmp.c functions from cache.h
ws.h: move declarations for ws.c functions from cache.h
match-trees.h: move declarations for match-trees.c functions from cache.h
pkt-line.h: move declarations for pkt-line.c functions from cache.h
base85.h: move declarations for base85.c functions from cache.h
copy.h: move declarations for copy.c functions from cache.h
server-info.h: move declarations for server-info.c functions from cache.h
packfile.h: move pack_window and pack_entry from cache.h
...
Mark strtok() and strtok_r() to be banned.
* tb/ban-strtok:
banned.h: mark `strtok()` and `strtok_r()` as banned
t/helper/test-json-writer.c: avoid using `strtok()`
t/helper/test-oidmap.c: avoid using `strtok()`
t/helper/test-hashmap.c: avoid using `strtok()`
string-list: introduce `string_list_setlen()`
string-list: multi-delimiter `string_list_split_in_place()`
When "gc" needs to retain unreachable objects, packing them into
cruft packs (instead of exploding them into loose object files) has
been offered as a more efficient option for some time. Now the use
of cruft packs has been made the default and no longer considered
an experimental feature.
* tb/enable-cruft-packs-by-default:
repository.h: drop unused `gc_cruft_packs`
builtin/gc.c: make `gc.cruftPacks` enabled by default
t/t9300-fast-import.sh: prepare for `gc --cruft` by default
t/t6500-gc.sh: add additional test cases
t/t6500-gc.sh: refactor cruft pack tests
t/t6501-freshen-objects.sh: prepare for `gc --cruft` by default
t/t5304-prune.sh: prepare for `gc --cruft` by default
builtin/gc.c: ignore cruft packs with `--keep-largest-pack`
builtin/repack.c: fix incorrect reference to '-C'
pack-write.c: plug a leak in stage_tmp_packfiles()
These are conscious violations of the usual rules for error messages,
based on this reasoning:
- If an error message is directly followed by another sentence, it
needs to be properly terminated with a period, lest the grammar
looks broken and becomes hard to read.
- That second sentence isn't actually an error message any more, so
it should abide to conventional language rules for good looks and
legibility. Arguably, these should be converted to advice
messages (which the user can squelch, too), but that's a much
bigger effort to get right.
- Neither of these apply to the first hunk in do_exec(), but this
two-line message looks just too much like a real sentence to not
terminate it. Also, leaving it alone would make it asymmetrical
to the other hunk.
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The on-disk reverse index that allows mapping from the pack offset
to the object name for the object stored at the offset has been
enabled by default.
* tb/pack-revindex-on-disk:
t: invert `GIT_TEST_WRITE_REV_INDEX`
config: enable `pack.writeReverseIndex` by default
pack-revindex: introduce `pack.readReverseIndex`
pack-revindex: introduce GIT_TEST_REV_INDEX_DIE_ON_DISK
pack-revindex: make `load_pack_revindex` take a repository
t5325: mark as leak-free
pack-write.c: plug a leak in stage_tmp_packfiles()
Geometric repacking ("git repack --geometric=<n>") in a repository
that borrows from an alternate object database had various corner
case bugs, which have been corrected.
* ps/fix-geom-repack-with-alternates:
repack: disable writing bitmaps when doing a local repack
repack: honor `-l` when calculating pack geometry
t/helper: allow chmtime to print verbosely without modifying mtime
pack-objects: extend test coverage of `--stdin-packs` with alternates
pack-objects: fix error when same packfile is included and excluded
pack-objects: fix error when packing same pack twice
pack-objects: split out `--stdin-packs` tests into separate file
repack: fix generating multi-pack-index with only non-local packs
repack: fix trying to use preferred pack in alternates
midx: fix segfault with no packs and invalid preferred pack
The code to parse capability list for v0 on-wire protocol fell into
an infinite loop when a capability appears multiple times, which
has been corrected.
* jk/protocol-cap-parse-fix:
v0 protocol: use size_t for capability length/offset
t5512: test "ls-remote --heads --symref" filtering with v0 and v2
t5512: allow any protocol version for filtered symref test
t5512: add v2 support for "ls-remote --symref" test
v0 protocol: fix sha1/sha256 confusion for capabilities^{}
t5512: stop referring to "v1" protocol
v0 protocol: fix infinite loop when parsing multi-valued capabilities
Header clean-up.
* en/header-split-cache-h: (24 commits)
protocol.h: move definition of DEFAULT_GIT_PORT from cache.h
mailmap, quote: move declarations of global vars to correct unit
treewide: reduce includes of cache.h in other headers
treewide: remove double forward declaration of read_in_full
cache.h: remove unnecessary includes
treewide: remove cache.h inclusion due to pager.h changes
pager.h: move declarations for pager.c functions from cache.h
treewide: remove cache.h inclusion due to editor.h changes
editor: move editor-related functions and declarations into common file
treewide: remove cache.h inclusion due to object.h changes
object.h: move some inline functions and defines from cache.h
treewide: remove cache.h inclusion due to object-file.h changes
object-file.h: move declarations for object-file.c functions from cache.h
treewide: remove cache.h inclusion due to git-zlib changes
git-zlib: move declarations for git-zlib functions from cache.h
treewide: remove cache.h inclusion due to object-name.h changes
object-name.h: move declarations for object-name.c functions from cache.h
treewide: remove unnecessary cache.h inclusion
treewide: be explicit about dependence on mem-pool.h
treewide: be explicit about dependence on oid-array.h
...
Enhance `string_list_split_in_place()` to accept multiple characters as
delimiters instead of a single character.
Instead of using `strchr(2)` to locate the first occurrence of the given
delimiter character, `string_list_split_in_place_multi()` uses
`strcspn(2)` to move past the initial segment of characters comprised of
any characters in the delimiting set.
When only a single delimiting character is provided, `strpbrk(2)` (which
is implemented with `strcspn(2)`) has equivalent performance to
`strchr(2)`. Modern `strcspn(2)` implementations treat an empty
delimiter or the singleton delimiter as a special case and fall back to
calling strchrnul(). Both glibc[1] and musl[2] implement `strcspn(2)`
this way.
This change is one step to removing `strtok(2)` from the tree. Note that
`string_list_split_in_place()` is not a strict replacement for
`strtok()`, since it will happily turn sequential delimiter characters
into empty entries in the resulting string_list. For example:
string_list_split_in_place(&xs, "foo:;:bar:;:baz", ":;", -1)
would yield a string list of:
["foo", "", "", "bar", "", "", "baz"]
Callers that wish to emulate the behavior of strtok(2) more directly
should call `string_list_remove_empty_items()` after splitting.
To avoid regressions for the new multi-character delimter cases, update
t0063 in this patch as well.
[1]: https://sourceware.org/git/?p=glibc.git;a=blob;f=string/strcspn.c;hb=glibc-2.37#l35
[2]: https://git.musl-libc.org/cgit/musl/tree/src/string/strcspn.c?h=v1.2.3#n11
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
hash.h depends upon and includes repository.h, due to the definition and
use of the_hash_algo (defined as the_repository->hash_algo). However,
most headers trying to include hash.h are only interested in the layout
of the structs like object_id. Move the parts of hash.h that do not
depend upon repository.h into a new file hash-ll.h (the "low level"
parts of hash.h), and adjust other files to use this new header where
the convenience inline functions aren't needed.
This allows hash.h and object.h to be fairly small, minimal headers. It
also exposes a lot of hidden dependencies on both path.h (which was
brought in by repository.h) and repository.h (which was previously
implicitly brought in by object.h), so also adjust other files to be
more explicit about what they depend upon.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git branch --format=..." and "git format-patch --format=..."
learns "--omit-empty" to hide refs that whose formatting result
becomes an empty string from the output.
* ow/ref-filter-omit-empty:
branch, for-each-ref, tag: add option to omit empty lines
Git authentication with OAuth access token is supported by every popular
Git host including GitHub, GitLab and BitBucket [1][2][3]. Credential
helpers Git Credential Manager (GCM) and git-credential-oauth generate
OAuth credentials [4][5]. Following RFC 6749, the application prints a
link for the user to authorize access in browser. A loopback redirect
communicates the response including access token to the application.
For security, RFC 6749 recommends that OAuth response also includes
expiry date and refresh token [6]. After expiry, applications can use
the refresh token to generate a new access token without user
reauthorization in browser. GitLab and BitBucket set the expiry at two
hours [2][3]. (GitHub doesn't populate expiry or refresh token.)
However the Git credential protocol has no attribute to store the OAuth
refresh token (unrecognised attributes are silently discarded). This
means that the user has to regularly reauthorize the helper in browser.
On a browserless system, this is particularly intrusive, requiring a
second device.
Introduce a new attribute oauth_refresh_token. This is especially
useful when a storage helper and a read-only OAuth helper are configured
together. Recall that `credential fill` calls each helper until it has a
non-expired password.
```
[credential]
helper = storage # eg. cache or osxkeychain
helper = oauth
```
The OAuth helper can use the stored refresh token forwarded by
`credential fill` to generate a fresh access token without opening the
browser. See
https://github.com/hickford/git-credential-oauth/pull/3/files
for an implementation tested with this patch.
Add support for the new attribute to credential-cache. Eventually, I
hope to see support in other popular storage helpers.
Alternatives considered: ask helpers to store all unrecognised
attributes. This seems excessively complex for no obvious gain.
Helpers would also need extra information to distinguish between
confidential and non-confidential attributes.
Workarounds: GCM abuses the helper get/store/erase contract to store the
refresh token during credential *get* as the password for a fictitious
host [7] (I wrote this hack). This workaround is only feasible for a
monolithic helper with its own storage.
[1] https://github.blog/2012-09-21-easier-builds-and-deployments-using-git-over-https-and-oauth/
[2] https://docs.gitlab.com/ee/api/oauth2.html#access-git-over-https-with-access-token
[3] https://support.atlassian.com/bitbucket-cloud/docs/use-oauth-on-bitbucket-cloud/#Cloning-a-repository-with-an-access-token
[4] https://github.com/GitCredentialManager/git-credential-manager
[5] https://github.com/hickford/git-credential-oauth
[6] https://datatracker.ietf.org/doc/html/rfc6749#section-5.1
[7] 66b94e489a/src/shared/GitLab/GitLabHostProvider.cs (L207)
Signed-off-by: M Hickford <mirth.hickford@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git clone --local" stops copying from an original repository that
has symbolic links inside its $GIT_DIR; an error message when that
happens has been updated.
* gc/better-error-when-local-clone-fails-with-symlink:
clone: error specifically with --local and symlinked objects
Code clean-up to replace a hardcoded constant with a CPP macro.
* rs/get-tar-commit-id-use-defined-const:
get-tar-commit-id: use TYPEFLAG_GLOBAL_HEADER instead of magic value
Back in 5b92477f89 (builtin/gc.c: conditionally avoid pruning objects
via loose, 2022-05-20), `git gc` learned the `--cruft` option and
`gc.cruftPacks` configuration to opt-in to writing cruft packs when
collecting or pruning unreachable objects.
Cruft packs were introduced with the merge in a50036da1a (Merge branch
'tb/cruft-packs', 2022-06-03). They address the problem of "loose object
explosions", where Git will write out many individual loose objects when
there is a large number of unreachable objects that have not yet aged
past `--prune=<date>`.
Instead of keeping track of those unreachable yet recent objects via
their loose object file's mtime, cruft packs collect all unreachable
objects into a single pack with a corresponding `*.mtimes` file that
acts as a table to store the mtimes of all unreachable objects. This
prevents the need to store unreachable objects as loose as they age out
of the repository, and avoids the problem of loose object explosions.
Beyond avoiding loose object explosions, cruft packs also act as a more
efficient mechanism to store unreachable objects as they age out of a
repository. This is because pairs of similar unreachable objects serve
as delta bases for one another.
In 5b92477f89, the feature was introduced as experimental. Since then,
GitHub has been running these patches in every repository generating
hundreds of millions of cruft packs along the way. The feature is
battle-tested, and avoids many pathological cases such as above. Users
who either run `git gc` manually, or via `git maintenance` can benefit
from having cruft packs.
As such, enable cruft pack generation to take place by default (by
making `gc.cruftPacks` have the default of "true" rather than "false).
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When cruft packs were implemented, we never adjusted the code for `git
gc`'s `--keep-largest-pack` and `gc.bigPackThreshold` to ignore cruft
packs. This option and configuration option share a common
implementation, but including cruft packs is wrong in both cases:
- Running `git gc --keep-largest-pack` in a repository where the
largest pack is the cruft pack itself will make it impossible for
`git gc` to prune objects, since the cruft pack itself is kept.
- The same is true for `gc.bigPackThreshold`, if the size of the cruft
pack exceeds the limit set by the caller.
In the future, it is possible that `gc.bigPackThreshold` could be used
to write a separate cruft pack containing any new unreachable objects
that entered the repository since the last time a cruft pack was
written.
There are some complexities to doing so, mainly around handling
pruning objects that are in an existing cruft pack that is above the
threshold (which would either need to be rewritten, or else delay
pruning). Rewriting a substantially similar cruft pack isn't ideal, but
it is significantly better than the status-quo.
If users have large cruft packs that they don't want to rewrite, they
can mark them as `*.keep` packs. But in general, if a repository has a
cruft pack that is so large it is slowing down GC's, it should probably
be pruned anyway.
In the meantime, ignore cruft packs in the common implementation for
both of these options, and add a pair of tests to prevent any future
regressions here.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When cruft packs were originally being developed, `-C` was designated as
the short-form for `--cruft` (as in `git repack -C`).
This was dropped due to confusion with Git's top-level `-C` option
before submitting to the list. But the reference to it in
`--cruft-expiration`'s help text was never updated. Fix that dangling
reference in this patch.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Clean-up of the code path that deals with merge strategy option
handling in "git rebase".
* pw/rebase-cleanup-merge-strategy-option-handling:
rebase: remove a couple of redundant strategy tests
rebase -m: fix serialization of strategy options
rebase -m: cleanup --strategy-option handling
sequencer: use struct strvec to store merge strategy options
rebase: stop reading and writing unnecessary strategy state
"git branch -d origin/master" would say "no such branch", but it is
likely a missed "-r" if refs/remotes/origin/master exists. The
command has been taught to give such a hint in its error message.
* cm/branch-delete-error-message-update:
branch: improve error log on branch not found by checking remotes refs
"git mergetool" and "git difftool" learns a new configuration
guiDefault to optionally favor configured guitool over non-gui-tool
automatically when $DISPLAY is set.
* tk/mergetool-gui-default-config:
mergetool: new config guiDefault supports auto-toggling gui by DISPLAY
While parsing a .rev file, we check the header information to be sure it
makes sense. This happens before doing any additional validation such as
a checksum or value check. In order to differentiate between a bad
header and a non-existent file, we need to update the API for loading a
reverse index.
Make load_pack_revindex_from_disk() non-static and specify that a
positive value means "the file does not exist" while other errors during
parsing are negative values. Since an invalid header prevents setting up
the structures we would use for further validations, we can stop at that
point.
The place where we can distinguish between a missing file and a corrupt
file is inside load_revindex_from_disk(), which is used both by pack
rev-indexes and multi-pack-index rev-indexes. Some tests in t5326
demonstrate that it is critical to take some conditions to allow
positive error signals.
Add tests that check the three header values.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'fsck' builtin checks many of Git's on-disk data structures, but
does not currently validate the pack rev-index files (a .rev file to
pair with a .pack and .idx file).
Before doing a more-involved check process, create the scaffolding
within builtin/fsck.c to have a new error type and add that error type
when the API method verify_pack_revindex() returns an error. That method
does nothing currently, but we will add checks to it in later changes.
For now, check that 'git fsck' succeeds without any errors in the normal
case. Future checks will be paired with tests that corrupt the .rev file
appropriately.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When parsing server capabilities, we use "int" to store lengths and
offsets. At first glance this seems like a spot where our parser may be
confused by integer overflow if somebody sent us a malicious response.
In practice these strings are all bounded by the 64k limit of a
pkt-line, so using "int" is OK. However, it makes the code simpler to
audit if they just use size_t everywhere. Note that because we take
these parameters as pointers, this also forces many callers to update
their declared types.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In order to write a bitmap, we need to have full coverage of all objects
that are about to be packed. In the traditional non-multi-pack-index
world this meant we need to do a full repack of all objects into a
single packfile. But in the new multi-pack-index world we can get away
with writing bitmaps when we have multiple packfiles as long as the
multi-pack-index covers all objects.
This is not always the case though. When asked to perform a repack of
local objects, only, then we cannot guarantee to have full coverage of
all objects regardless of whether we do a full repack or a repack with a
multi-pack-index. The end result is that writing the bitmap will fail in
both worlds:
$ git multi-pack-index write --stdin-packs --bitmap <packfiles
warning: Failed to write bitmap index. Packfile doesn't have full closure (object 1529341d78cf45377407369acb0f4ff2b5cdae42 is missing)
error: could not write multi-pack bitmap
Now there are two different ways to fix this. The first one would be to
amend git-multi-pack-index(1) to disable writing bitmaps when we notice
that we don't have full object coverage.
- We don't have enough information in git-multi-pack-index(1) in
order to tell whether the local repository _should_ have full
coverage. Because even when connected to an alternate object
directory, it may be the case that we still have all objects
around in the main object database.
- git-multi-pack-index(1) is quite a low-level tool. Automatically
disabling functionality that it was asked to provide does not feel
like the right thing to do.
We can easily fix it at a higher level in git-repack(1) though. When
asked to only include local objects via `-l` and when connected to an
alternate object directory then we will override the user's ask and
disable writing bitmaps with a warning. This is similar to what we do in
git-pack-objects(1), where we also disable writing bitmaps in case we
omit an object from the pack.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the user passes `-l` to git-repack(1), then they essentially ask us
to only repack objects part of the local object database while ignoring
any packfiles part of an alternate object database. And we in fact honor
this bit when doing a geometric repack as the resulting packfile will
only ever contain local objects.
What we're missing though is that we don't take locality of packfiles
into account when computing whether the geometric sequence is intact or
not. So even though we would only ever roll up local packfiles anyway,
we could end up trying to repack because of non-local packfiles. This
does not make much sense, and in the worst case it can cause us to try
and do the geometric repack over and over again because we're never able
to restore the geometric sequence.
Fix this bug by honoring whether the user has passed `-l`. If so, we
skip adding any non-local packfiles to the pack geometry.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When passing the same packfile both as included and excluded via the
`--stdin-packs` option, then we will return an error because the
excluded packfile cannot be found. This is because we will only set the
`util` pointer for the included packfile list if it was found, so that
we later die when we notice that it's in fact not set for the excluded
packfile list.
Fix this bug by always setting the `util` pointer for both the included
and excluded list entries.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When passed the same packfile twice via `--stdin-packs` we return an
error that the packfile supposedly was not found. This is because when
reading packs into the list of included or excluded packfiles, we will
happily re-add packfiles even if they are part of the lists already. And
while the list can now contain duplicates, we will only set the `util`
pointer of the first list entry to the `packed_git` structure. We notice
that at a later point when checking that all list entries have their
`util` pointer set and die with an error.
While this is kind of a nonsensical request, this scenario can be hit
when doing geometric repacks. When a repository is connected to an
alternate object directory and both have the exact same packfile then
both would get added to the geometric sequence. And when we then decide
to perform the repack, we will invoke git-pack-objects(1) with the same
packfile twice.
Fix this bug by removing any duplicates from both the included and
excluded packs.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When writing the multi-pack-index with geometric repacking we will add
all packfiles to the index that are part of the geometric sequence. This
can potentially also include packfiles borrowed from an alternate object
directory. But given that a multi-pack-index can only ever include packs
that are part of the main object database this does not make much sense
whatsoever.
In the edge case where all packfiles are contained in the alternate
object database and the local repository has none itself this bug can
cause us to invoke git-multi-pack-index(1) with only non-local packfiles
that it ultimately cannot find. This causes it to return an error and
thus causes the geometric repack to fail.
Fix the code to skip non-local packfiles.
Co-authored-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When doing a geometric repack with multi-pack-indices, then we ask
git-multi-pack-index(1) to use the largest packfile as the preferred
pack. It can happen though that the largest packfile is not part of the
main object database, but instead part of an alternate object database.
The result is that git-multi-pack-index(1) will not be able to find the
preferred pack and print a warning. It then falls back to use the first
packfile that the multi-pack-index shall reference.
Fix this bug by only considering packfiles as preferred pack that are
local. This is the right thing to do given that a multi-pack-index
should never reference packfiles borrowed from an alternate.
While at it, rename the function `get_largest_active_packfile()` to
`get_preferred_pack()` to better document its intent.
Helped-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If the given format string expands to the empty string, a newline is
still printed. This makes using the output linewise more tedious. For
example, git update-ref --stdin does not accept empty lines.
Add options to "git branch", "git for-each-ref", and "git tag" to
not print these empty lines. The default behavior remains the same.
Signed-off-by: Øystein Walle <oystwa@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Back in e8c58f894b (t: support GIT_TEST_WRITE_REV_INDEX, 2021-01-25), we
added a test knob to conditionally enable writing a ".rev" file when
indexing a pack. At the time, this was used to ensure that the test
suite worked even when ".rev" files were written, which served as a
stress-test for the on-disk reverse index implementation.
Now that reading from on-disk ".rev" files is enabled by default, the
test knob `GIT_TEST_WRITE_REV_INDEX` no longer has any meaning.
We could get rid of the option entirely, but there would be no
convenient way to test Git when ".rev" files *aren't* in place.
Instead of getting rid of the option, invert its meaning to instead
disable writing ".rev" files, thereby running the test suite in a mode
where the reverse index is generated from scratch.
This ensures that, when GIT_TEST_NO_WRITE_REV_INDEX is set to some
spelling of "true", we are still running and exercising Git's behavior
when forced to generate reverse indexes from scratch. Do so by setting
it in the linux-TEST-vars CI run to ensure that we are maintaining good
coverage of this now-legacy code.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Back in e37d0b8730 (builtin/index-pack.c: write reverse indexes,
2021-01-25), Git learned how to read and write a pack's reverse index
from a file instead of in-memory.
A pack's reverse index is a mapping from pack position (that is, the
order that objects appear together in a ".pack") to their position in
lexical order (that is, the order that objects are listed in an ".idx"
file).
Reverse indexes are consulted often during pack-objects, as well as
during auxiliary operations that require mapping between pack offsets,
pack order, and index index.
They are useful in GitHub's infrastructure, where we have seen a
dramatic increase in performance when writing ".rev" files[1]. In
particular:
- an ~80% reduction in the time it takes to serve fetches on a popular
repository, Homebrew/homebrew-core.
- a ~60% reduction in the peak memory usage to serve fetches on that
same repository.
- a collective savings of ~35% in CPU time across all pack-objects
invocations serving fetches across all repositories in a single
datacenter.
Reverse indexes are also beneficial to end-users as well as forges. For
example, the time it takes to generate a pack containing the objects for
the 10 most recent commits in linux.git (representing a typical push) is
significantly faster when on-disk reverse indexes are available:
$ { git rev-parse HEAD && printf '^' && git rev-parse HEAD~10 } >in
$ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} pack-objects --delta-base-offset --revs --stdout <in >/dev/null'
Benchmark 1: git.compile -c pack.readReverseIndex=false pack-objects --delta-base-offset --revs --stdout <in >/dev/null
Time (mean ± σ): 543.0 ms ± 20.3 ms [User: 616.2 ms, System: 58.8 ms]
Range (min … max): 521.0 ms … 577.9 ms 10 runs
Benchmark 2: git.compile -c pack.readReverseIndex=true pack-objects --delta-base-offset --revs --stdout <in >/dev/null
Time (mean ± σ): 245.0 ms ± 11.4 ms [User: 335.6 ms, System: 31.3 ms]
Range (min … max): 226.0 ms … 259.6 ms 13 runs
Summary
'git.compile -c pack.readReverseIndex=true pack-objects --delta-base-offset --revs --stdout <in >/dev/null' ran
2.22 ± 0.13 times faster than 'git.compile -c pack.readReverseIndex=false pack-objects --delta-base-offset --revs --stdout <in >/dev/null'
The same is true of writing a pack containing the objects for the 30
most-recent commits:
$ { git rev-parse HEAD && printf '^' && git rev-parse HEAD~30 } >in
$ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} pack-objects --delta-base-offset --revs --stdout <in >/dev/null'
Benchmark 1: git.compile -c pack.readReverseIndex=false pack-objects --delta-base-offset --revs --stdout <in >/dev/null
Time (mean ± σ): 866.5 ms ± 16.2 ms [User: 1414.5 ms, System: 97.0 ms]
Range (min … max): 839.3 ms … 886.9 ms 10 runs
Benchmark 2: git.compile -c pack.readReverseIndex=true pack-objects --delta-base-offset --revs --stdout <in >/dev/null
Time (mean ± σ): 581.6 ms ± 10.2 ms [User: 1181.7 ms, System: 62.6 ms]
Range (min … max): 567.5 ms … 599.3 ms 10 runs
Summary
'git.compile -c pack.readReverseIndex=true pack-objects --delta-base-offset --revs --stdout <in >/dev/null' ran
1.49 ± 0.04 times faster than 'git.compile -c pack.readReverseIndex=false pack-objects --delta-base-offset --revs --stdout <in >/dev/null'
...and savings on trivial operations like computing the on-disk size of
a single (packed) object are even more dramatic:
$ git rev-parse HEAD >in
$ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} cat-file --batch-check="%(objectsize:disk)" <in'
Benchmark 1: git.compile -c pack.readReverseIndex=false cat-file --batch-check="%(objectsize:disk)" <in
Time (mean ± σ): 305.8 ms ± 11.4 ms [User: 264.2 ms, System: 41.4 ms]
Range (min … max): 290.3 ms … 331.1 ms 10 runs
Benchmark 2: git.compile -c pack.readReverseIndex=true cat-file --batch-check="%(objectsize:disk)" <in
Time (mean ± σ): 4.0 ms ± 0.3 ms [User: 1.7 ms, System: 2.3 ms]
Range (min … max): 1.6 ms … 4.6 ms 1155 runs
Summary
'git.compile -c pack.readReverseIndex=true cat-file --batch-check="%(objectsize:disk)" <in' ran
76.96 ± 6.25 times faster than 'git.compile -c pack.readReverseIndex=false cat-file --batch-check="%(objectsize:disk)" <in'
In the more than two years since e37d0b8730 was merged, Git's
implementation of on-disk reverse indexes has been thoroughly tested,
both from users enabling `pack.writeReverseIndexes`, and from GitHub's
deployment of the feature. The latter has been running without incident
for more than two years.
This patch changes Git's behavior to write on-disk reverse indexes by
default when indexing a pack, which should make the above operations
faster for everybody's Git installation after a repack.
(The previous commit explains some potential drawbacks of using on-disk
reverse indexes in certain limited circumstances, that essentially boil
down to a trade-off between time to generate, and time to access. For
those limited cases, the `pack.readReverseIndex` escape hatch can be
used).
[1]: https://github.blog/2021-04-29-scaling-monorepo-maintenance/#reverse-indexes
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git clone" from an empty repository learned to propagate the
choice of the hash algorithm from the source repository to the
newly created repository.
* jc/clone-object-format-from-void:
clone: propagate object-format when cloning from void
"git sparse-checkout" command learns a debugging aid for the sparse
rule definitions.
* ws/sparse-check-rules:
builtin/sparse-checkout: add check-rules command
builtin/sparse-checkout: remove NEED_WORK_TREE flag
cache.h's nature of a dumping ground of includes prevented it from
being included in some compat/ files, forcing us into a workaround
of having a double forward declaration of the read_in_full() function
(see commit 14086b0a13 ("compat/pread.c: Add a forward declaration to
fix a warning", 2007-11-17)). Now that we have moved functions like
read_in_full() from cache.h to wrapper.h, and wrapper.h isn't littered
with unrelated and scary #defines, get rid of the extra forward
declaration and just have compat/pread.c include wrapper.h.
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
cache.h and strbuf.[ch] had editor-related functions. Move these into
editor.[ch].
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Move functions from cache.h for zlib.c into a new header file. Since
adding a "zlib.h" would cause issues with the real zlib, rename zlib.c
to git-zlib.c while we are at it.
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
